Thermally-actuated circuit-controller



Sept. 8, 1931. w. D. KING 1,822,408

THERMALLY ACTUATED CIRCUIT CONTROLLER Filed Nov. 28, 1927 l jenor,

www5@ Patented Sept. 8, y1931 UNITED STATES PATENT oFFlcE SAID WARREN D.

KING, DECEASED THERMALLY-ACTUATED CIRCUIT-CONTROLLE Application filedNovember 28, 1927. Serial No. 236,111.,

This invention relates to thermally-actuated circuit controllers andespecially to those having `a thermally eXpansible iuid body whichoperates the Controller.

The usual type of thermostatic circuit controller includes a pair ofcooperating contact members which are separated to interrupt theircircuit by the expansion of an expansible member due to the heatingthereof. The rate of expansion is slow and, as a consequence, thecontact members are moved apart slowly. thus drawn andmaintained betweenthe contact members for a considerable period of time which, atleast, islong en-ough to cause burning and pitting of the contact surfaces, sothat 'the electrical contactv between the contact members becomesuncertain and frequent inspection and adjustment becomes necessary.

An object of this invention ispthe provision of a thermally-actuatedcircuit-controller wherein the separable Contact members are immersedand the circuit-,interrupting arc isy drawn in a body of electricallyinsulating liquid which acts to quench the arc immediately upon theseparation of ther contact members under load, thus to keep the contactmembers cool and prevent deterioration of the contact surfaces, so thatthe controller can imction for an indefinite period-without attention.

A further object is the provision of a thermally-actuatedcircuit-controller having contact members which are separated vby .thethermal expansion of an eXpansible liquid which als-o constitutes theelectrically insu lating liquid in which 'the contact members areimmersed andin which the circuit-interrupting arc is drawn.

A yet further object of theJ invention 1s the provision of athermostatic circuit-controller of the eXpansible liquid type havingmeans to vary the (volume of the liquid-enclosing container, whereby toset the controller Jfor operation at various degrees of temperature.

Another Objectis generally to improve they construction and operation ofthe. thermallyactuated circuit-controllers.

A circuit-interrupting arc is Fig. 1 is a sectional elevation of anelectrically-heated flat-iron with which the thermally-actuatedcircuit-controller embodying this invention is associated.

Fig. 2 is a sectional; elevation through the thermally-actuatedcircuit-controller of Fig. 1.

Mig. 3 is a plan view of the controller of Fig. 2.

Fig. 4 is a side elevation of the flexible diaphragm and movable contactmember of the thermally-actuated circuit-controller. n

The' thermally-actuated circuit-controller here shown as embodying theinvention includes a casingy l0 which has a top-opening and has acylindrical side wall l2 and a lat bottom wall la integral with saidside wall. Said walls aretluid impermeable and rigid and are composed ofa good heat-conducting material, as steel, for instance. The top portionof the side wall 12 is provided with an internal annular recess 16 whichis internally screw-threaded and terminates at the bottom in an annularseat 18 which is inclined slightly downward and inward toward theinterior of the casing. A plane flexible disc or diaphragm 20 is seatedon said seat 18 and is clamped securely thereon in iuid tight engagementwith the casing by a clamping ring 22 which is externally screw-threadedand is secured into the annular recess 16 and against the upper face ofthe diaphragm. The lower annular face 2a of said clamping ring is formedto correspond with the seat 18 so that the diaphragm is flexed in themanner illustrated in F ig. 2 and thus applies substantial pressure tothe separable contact members described below. y

rlhe diaphragm carries a movable contact member 26 which is locatedwithin the casing under the diaphragm and is tiXed to the lower end of ascrew-threadedrod 28 that is ad-` justably screw-threaded in an`insulating bushing 30 extended through and iXed to the middle ot' saiddiaphragm in a Huid-tight manner. A checknut 32 is screw-threaded onsaid rod and bears against the upper end of said bushing to hold saidrod in set adjustment and also to prevent leakage of fluid from theinterior of the casing about the rod.

A second nut 34'serves to clamp a suitable circuit lead between it andthe nut 32. The

upper exposed end of the rod has a screwdriver slot 36 therein forrotating the -rod to adjust the contact members.'

Said movable contact member cooperates with a similar contact member 38xed to the upper end of a screw 40 which is screwthreaded into aninsulating bushing 42 which has a fluid-tight screw-threaded connectionwith the bottom wall 14 of the casing. A second circuit lead is adaptedto be clamped between the head of said screw 40 and said bushing and tobe extended through an outwardly extended passage 44 in said bottom wall14 to a point externally of the casing.

rIhe internal volume of the casing can be varied by an adjusting screw46 which is extended through a passage 48 in the side wall 12 of thecasing, near the bottom thereof, and is adjustably screw-threaded in abushing 50 which is screw-threaded in said passage. A packing material52 is disposed etween the inner end of said bushing and the annularledge 54 located at the inner end of said passage to seal the passageagainst fluid leakage therethrough.

The casing 1s adapted to be illed with an electrically-insulatingexpansible liquid which does not give off a harmful amount of vapor at,or has a boiling point which is higher than, the elevatedtemperature...at which the device is adapted to be operated.

The particular device is here shown for interrupting the circuit of anelectrically heated flat iron when the temperature thereof becomesexcessive as, say, around 575 F. For this particular service, theexpansible liquid can be a high boiling point mineral 'oil.' Foroperation at lower temperatures,

the same liquid can be employed or, if desirable, other suitableliquids, as lighter oils, can be used. In all cases, however, theexpansible liquid is characterized by being electricall insulating sothat when the contact mem ers are separated under load, by the flexingof the diaphragm, the liquid occupies the space between the separatedcontact members and immediately extinguishes the circuit interruptingarc and prevents the passage of any material current through the circuitcontrolled by the contact members.

In adjusting the device for operation at some selected elevatedtemperature, the casing preferably is entirely filled with the liquid,so that it is in contact with., the diaphragm. The adjusting screw isthen backed out of the casing by an amount determined by experience ortrial so that the. oil level is lowered somewhat, or there is a smallevacuated space above the oil and under the diaphragm or portionsthereof. The oi l can thus expand and fill the space without moving thediaphragm. On a further increase 65 in temperature, however, theexpanding oil acts with pressure on and forces the diaphragm outwardlyand separates the con`- tact members andthe oil is eiective inpreventing continued arcing between the separated contact members. Whenthe temperature falls, the oil `contracts and the contact members againengage and are pressed forcibly together due to the tension on thediaphragm. 4

The device herein illustrated is especially adapted for use in anelectric iron, lto prevent the overheating thereof and is received in awell 58 in the body 60 of the iron, under the cover 62, and is in serieswith the heater element 64 and is adapted to be heated there- 80 by, Itis apparent that an excessive rise in temperature will cause theactuation of the circuit-controller and interrupt the circuitv of theheater element and also will automatically close the circuit when thetemperature I falls to some lower value, thus automatically maintainingthe temperature of the iron between certain upper and lower` limits.

The temperature-adjusting screw 46 is accessible by a screw driverinserted through 00 an aperture 66 in the cover covered by a plate 68,which may be a name-plate, and a passage 70 in the body of the iron. Thedevice thus can be adjusted While it is in place in the iron. y

The device may be otherwise arranged without departing from the spiritof the invention. l

I claim: y 1 A thermally-actuated circuit controller 1`00 includingseparable contact members, a diaphragm for operating said contactmembers,

a casing enclosing said contact members, and

an electrically-insulating thermally-expansible liquid in which saidcontact members are immersed, which liquid when hot completely fillssaid casing and forcibly expands directly against said diaphragm andmoves it to operate said contact members.

, 2. A thermally-actuated circuit-controller no having athermally-expan'sible, electricallyinsulatin liquid, separable contactlmembers immerse in said liquid, and means 4responsive directly to theexpansion of said liquid, lwhen heated, to operate said contact memers.

3. A thermally-actuated circuit-controller having a body ofthermally-expansible liquid -which has a boiling point higher than thehighest temperature to which the controller is ada ted to be subjected,contact members separa le beneath saidliquid by the expansion thereof,and means responsive directl to the expansion of said liquid, when heateto operate said contact members.

4. A thermally-actuated circuit-controller having a receptacle adaptedto be completely filled with an ex ansible liquid when it 1s hot,contact mem ers disposed within said receptacle and separable withinsaid liquid, 130

and operating mechanism for said contact members operated directly byexpansion of said liquid.

5. A thermally-actuated circuit controller including separable contactmembers, operating mechanism therefor including a liquidactuated member,and means to operate said contact members including an insulatingthermally-expansible liquid in which said contact members are immersedand Which forcibly expands directly against said liquidhaving a casingadapted to be completely filled with an eXpansible liquid when it ishot, said casing having a Wall which is moved directly by the expansionof said liquid, cooperating contact members separable in said liquid andoperated by said expansible Wall, and means to v ary the volume'of saidcasing including a member movable in and out of said casing.

8. A thermally-actuated circuit controller including separable contactmembers, a casing enclosing said contact members having a diaphragm foroperating said contact members which has its inner face open to theinterior of the casing and its outer face open to the atmosphere, and anelectrically-insulating thermally-expansible liquid having a highyboiling point contained in said caslng andy in which said contactmembers are immersed, said liquid When hot completelyfilling ysaidcasing and forcibly expanding directly against said diaphragm to forceit out- Wardly and separate said contact members and When coldincompletely filling said casing so that there is a vacuum Within saidcasing whereby atmospheric pressure acts on said diaphragm to hold saidcontact members forcibly in engagement.

9. A thermally-actuated circuit control forA a heat conducting bodyhaving a Well therein and an electrical heating element associatedtherewith to heat it, comprising an expansible-fiuid containing casingreceived in said Well having separable contact members immersed in thefluid and actuated by the expansion thereof, said casing having alaterally extended adjusting member received in a passage in said heatedbody communicating With said Well, and a cover for said body and casinghaving an opening therethrough in register With the entrance to saidpassage.

10. A thermally-actuated circuit controller including separable contactmembers, a

casing enclosing said contact members having a diaphragm for operatingsaid contact members Which has its inner face open to the interior ofthe casing and itsouter face open to the atmosphere, anelectrically-insulating thermally-expansible liquid having a highboiling point contained in said casing and in Which said contact membersare immersed, said liquid When hot completely filling said casing andforcibly expanding directly against said diaphragm to force it outwardlyand separate said contact members and When cold ineompletely fillingsaid casing so that there is a vacuum Within said casing wherebyatmospheric pressure acts on Said diaphragm to hold said contactimembers forcibly in engagement, and means to vary the amount ofexpansion of the liquid prior to completely filling the casing,including means to vary the volume of the casing.

In testimony Whereof,`I name to this specification.

WARREN D. KING.

have signed my

